# EPUBCheck CSS-007: non-standard font type, how to fix it

Source: https://epubcc.com/epubcheck/css-007/ (updated 2026-11-04)

EPUBCheck CSS-007 is an info message: “Font-face reference "…" refers to non-standard font type "…".” An @font-face rule points to a font in a format EPUB does not list as a core font type. EPUB's core font types are TrueType, OpenType, WOFF and WOFF2; other formats may be ignored and the text shown in a default font. EPUBCheck reports it as information.

- Official message (EPUBCheck 5.4.0): Font-face reference "%1$s" refers to non-standard font type "%2$s".
- Default severity: Info

## Typical causes

- Fonts in formats other than TrueType, OpenType, WOFF or WOFF2, such as EOT or SVG fonts.
- A font file listed in the manifest with an unusual media type.

## How to fix it

1. Open the file EPUBCheck names (the message gives the path, line and column) in a text or EPUB editor such as Sigil, or unzip the EPUB and open it there.
2. Convert the font to WOFF2, WOFF, OpenType or TrueType, if its licence allows embedding and conversion.
3. Update the src of the @font-face rule and the manifest item with the new file and media type (for example font/woff2).
4. Or remove the @font-face rule and let the reading app use its own fonts.
5. Rebuild the EPUB and run EPUBCheck again to confirm the message is gone.

## When it's not this

If the @font-face rule is empty, the warning is CSS-019.

## Sources

- EPUB 3.3, §3.2 Core media types: https://www.w3.org/TR/epub-33/#sec-core-media-types (read 2026-11-04)

Message text and severity: EPUBCheck (W3C, BSD-3-Clause). Explanation: EpubCC.